Results 1 - 10 of 1301
Results 1 - 10 of 1301. Search took: 0.021 seconds
|Sort by: date | relevance|
[en] The production of massive neutrinos by electrons moving in an external field in considered. The small neutrino mass is shown to greatly affect the probability of high-energy neutrino production of ultrarelativistic electrons. An entirely new experimental scheme for the discovery of neutrino mass is suggested and analyzed. 7 refs
[en] Correction to: Astrophys Space Sci (2013) 345:291–296 https://doi.org/10.1007/s10509-013-1403-8 There were typos in the last author’s name in the original publication. The name is correctly shown here.
[en] In this work, self-similar expansion of one-dimensional collisionless plasma into vacuum has been analytically calculated for non-Maxwellian particles. The calculations were carried out once with cold ions while having Lorentzian (kappa) distribution function (DF) for electrons and once with warm ions. The comparison of the results with the case of Maxwellian plasmas showed that the rate of expansion for the Maxwellian and kappa distributions differs substantially in high-energy tails. On the other hand, a more perfect and realistic DF including high-energy (super thermal) electrons has been modeled by kappa DF. It was found that, by increasing the population of energetic electrons, the expansion takes place faster and the ions are accelerated to higher energies. The effects of ions’ temperature have also been discussed through the paper. Finally, a relationship between “kappa” and “gamma” (polytropic exponent) has been defined and Lorentzian DF has been rewritten based on the polytropic exponent. Then a physical meaning has been defined for the “kappa” spectral index. Graphical abstract: .
[en] We report on the transverse refluxing of energetic electrons in mass-limited foil targets irradiated with high intensity (1 x 1019 W cm-2), picosecond laser pulses. It is shown experimentally that the maximum energies of protons accelerated by sheath fields formed at the rear and at the edges of the target increase with decreasing target size. This is due to the modification of the sheath field by the energetic electrons which spread laterally along the target surface and reflect from the edges. In addition, it is shown that this transverse refluxing of energetic electrons can be used to tailor the spatial-intensity distribution of the proton beam by engineering the shape and size of the target.
[en] Complete text of publication follows. At the relativistic region, the maximum energy of electrons is the ellipsoid model is about 25% more than the spherical model, and this is confirmed by PIC and the measured experimental results reported here. The electron energy spectrum is also calculated and it is found that the energy distribution ratio of electrons ΔE/E for the ellipsoid model in the here reported condition is much less that of the spherical model. This is in good agreement with the experimentally measured value in the same condition. In this regime, the parameters of the quasi-monoenergetic electrons output beam can be described more appropriately. In this work, intense femtosecond laser pulse was focused on the best matched point above He gas jet to obtain a stable ellipsoid bubble. The obtained monoenergetic electron energy spectrum is properly explained by the ellipsoid model introduced here. The presented ellipsoid cavity model is more consistent than the previous spherical model, and it explains the monoenergetic electron trajectory more accurately.
[en] Complete text of publication follows. In this study we focused on 9 targeted Titan flybys of Cassini between DOY 053-180 in 2007 (T25-T33). We analyzed the measurements of the Cassini MIMI-LEMMS and CAPS-IMS instruments, and also used the data of the onboard Magnetometer. During these flybys Titan was located at approximately the same position (at ∼13.5 SLT) along its orbit, the unique T32 - when the moon was found in Saturn's magnetosheath - was observed in this period as well. Since the relative positions of the dominant ionization sources (solar EUV, charge exchange, magnetospheric electron impacts) were similar during these flybys, it is reasonable to compare the measurements and get a more detailed picture of Titan's global plasma environment. The flybys were carried out during the high inclination phase of the Cassini Tour. Our analysis was focused on the differential intensities of energetic electrons and ions, and we also used the low energy ion measurements of CAPS-IMS. Another question that we investigated was concentrated on T32, during which the magnetosphere was significantly more compressed compared to the other flybys of this group. Therefore we analysed the possibility of a solar event reaching Saturn at this time. In April and May 2007 there were several active regions on the Sun, so we used plasma parameters measured by the Venus Express spacecraft (which was approximately along the Sun-Saturn line) to estimate whether the energetic particles of a CME erupted towards Saturn could have been responsible for the compression detected during T32.
[en] Here, the two stage electron acceleration model is extended to investigate the sources of super-hot electrons at intense circularly polarized (CP) laser solid interactions. It is found that in the presence of large scale pre-formed plasmas, super-high energetic electrons can be generated. For laser of intensity 1020 W/cm2 and pre-plasma of scale-length 10 μm, the cut-off energy of electrons by CP laser can be as high as 120 MeV compared with 100 MeV by linearly polarized laser. This unexpected acceleration can be also explained by the two-stage acceleration model. The envelop modulation of reflected CP laser is figured out, and a modified scaling law of the maximal-possible energy gain when including the modulation effect is obtained.
[en] As a part of the calorimeter system of the LHCb experiment both the Electromagnetic Calorimeter (ECAL) and the Hadron Calorimeter (HCAL) play a key role in the LHCb trigger system providing it with energetic electron, photon and hadron candidates. The article discusses the designs of both calorimeters and reports their present performance as it was obtained from the analysis of early data collected in the spring of 2010.
[en] By using a cone attached to a capillary, electrons generated through a laser interaction were autoinjected and accelerated in a low-density wake field. The cone attached to the entrance of the capillary serves as an electron supplier. It increases the number of electrons from below the detection limit to 1.1 pC and the energy from 4 to 30 MeV. A two-dimensional particle-in-cell simulation reveals that a significant number of energetic electrons are extracted from the surface of the cone and are subsequently trapped in the wake field and accelerated in the capillary.
[en] The influence of laser pulse duration on energetic electrons and protons generation was investigated using a Ti:sapphire laser. Energetic electrons with the temperature of 350 keV were produced by the irradiation of 90 mJ and 50 fs pulse onto a 30 μ m copper tape target. For ions, when laser pulse was changed by varying grating distance in the pulse compressor with keeping laser energy at constant value, the maximum proton energy was not changed so much in the region where laser pulse duration was between 55 fs and 400 fs and laser intensity was order of 1018 W/ cm2. The maximum proton energy seems to more depend on the laser energy density on the target than laser intensity. When we evaluate the performance of ion acceleration using the value of Ep-max/Up (the maximum proton energy normalized by the ponderomotive potential of the laser field), it increasing along with increasing of laser pulse duration.